Structural Features of Transmembrane Signaling in Plants

植物细胞表面信号的转换控制着植物的发育、激素反应、避免自花授粉和抗病性。 植物中的跨膜信号传导通过受体样激酶（RLK）CLAVATA 1与激酶相关蛋白磷酸酶（KAPP）的相互作用来例示。 这一对在质膜的内表面上相互作用，以指导模式植物拟南芥的茎和花分生组织的发育。KAPP FHA结构域如何与RLK激酶结构域相互作用的基本问题将在本项目中进行研究。 FHA结构域是一类新发现的磷酸丝氨酸/磷酸苏氨酸结合结构域，在真核生物中广泛存在于多种蛋白质-蛋白质信号传导环境中。 没有三维原子结构的KAPP或RLK的报告。NMR将用于确定KAPP的独特FHA结构域的两种形式的高质量结构：游离和与磷酸肽结合。磷酸肽与KAPP FHA结构域相互作用的特异性的序列决定因素将使用定点诱变，筛选磷酸/thr肽结合，和热力学的磷酸肽结合最亲的FHA结构域进行探索。 为了进一步探索KAPP如何与CLAVATA 1相互作用，将对该RLK的丝氨酸激酶结构域的结构进行建模。博士生的培训将通过接触约翰步行者实验室的补充植物遗传学研究和杰夫斯科尔尼克实验室的蛋白质建模来加强。 该项目将深入研究一类植物信号蛋白在信号转换过程中如何特异性地相互作用。它还将为其他生物体中FHA介导的蛋白质-蛋白质相互作用增添前景。

Switching of signals at the surface of plant cells controls plant development, hormone response, avoidance of self-pollination, and disease resistance. Transmembrane signaling in plants is exemplified by the interactions of the receptor-like kinase (RLK) CLAVATA1 with kinase-associated protein phosphatase (KAPP). This pair interacts on the inner surface of the plasma membrane to guide the development of the shoot and flower meristems of the model plant Arabidopsis. The fundamental question of how the KAPP FHA domain interacts with an RLK kinase domain will be investigated in this project. The FHA domain is a newly described class of phosphoserine / phosphothreonine-binding domain which is ubiquitous among eukaryotes in diverse protein-protein signaling contexts. No three-dimensional atomic structures of KAPP or of an RLK have been reported. NMR will be used to determine high quality structures of the distinctive FHA domain of KAPP in two forms: free and bound to a phosphopeptide. Sequence determinants of the specificity of phosphopeptide interactions with the KAPP FHA domain will be explored using site-directed mutagenesis, screening of phosphoser/thr peptide binding, and thermodynamics of the binding of phosphopeptides most avid for the FHA domain. To further probe how KAPP interacts with CLAVATA1, the structure of the serine kinase domain of this RLK will be modeled. The training of PhD students will be enhanced by exposure to complementary plant genetics studies in the lab of John Walker and to protein modeling in the lab of Jeff Skolnick. This project will provide insights into how a class of plant signaling proteins interacts specifically during the process of signal switching. It will also add perspective to FHA-mediated protein-protein interactions in other organisms.